A 12x5 teepad requires right around 3/4 of a cubic yard of concrete. Most trucks can carry around 9 cubic yards (I actually think that's the DOT limit in OH) so if you're doing 9 teepads you're going to be using close to a full load.

Right now, in N. KY, a cubic yard of concrete is going for right around $105/cubic yard give or take. (Delivered) That number can go up or down based on the precise mix you're going for. (PSI rating, air entrained or not, cold weather additives, etc.)

I recommend:

3000-3500 PSI, air entrained, water reducer admix at about a 5" slump

-or-

Tell your supplier you want city sidewalk mix. Which is exactly the kind of stress these pads will go under. Mostly foot traffic and the occasional lawn-mower or the like

In either case I see the OP is from Ohio and they will definitely want air entrainment which for that area I suspect the recommended amount is around 4.5-6%.

Nah...4000 isn't that overkill really so long as the supplier charging a stupid amount more.

Oh and another thing I see people overlook when installing pads - be sure to put them on a well compacted material like sand or road gravel and install them on a very slight slope one way or the other so water doesn't pond on them. 1% to 2% is about perfect where folks don't notice but it moves the water. 1% to 2% = 1' to 2' rise over 100' run -or- a 5' wide pad will need to have one side 0.6" to 1.2" higher than the other. Sounds like a lot but it really isn't. This is again, a lot like how a typical sidewalk is installed.

Air entrainment is putting tiny bubbles in the concrete so that when exposed to freeze/thaw cycles it can expand and contract as needed. Different regions of the country have different industry standards on the amount of air entrainment required. Here in Michigan you need 5.5% - 8%. The way you know is to ask your supplier for it and most of them like repeat business and not lawsuits so they'll put it in the mix and their delivery tickets will show if it entrainment is in there. If you don't have it the concrete will spall and deteriorate in the winter weather. There are tests for it (I've done hundreds of these tests) where you can get a an air meter to test for it. For a disc golf course however, that's going to be WAY outside of the budget to hire an engineering firm to do those tests.

tl:dr - get concrete from a reputable supplier and make sure they know its for outdoor use much like a sidewalk.